1. Field
The present disclosure relates to zoom lens systems, interchangeable lens apparatuses, and camera systems.
2. Description of the Related Art
In recent years, interchangeable-lens type digital camera systems (also referred to simply as “camera systems”, hereinafter) have been spreading rapidly. Such interchangeable-lens type digital camera systems realize: taking of high-sensitive and high-quality images; high-speed focusing and high-speed image processing after image taking; and easy replacement of an interchangeable lens apparatus in accordance with a desired scene. Meanwhile, an interchangeable lens apparatus having a zoom lens system that forms an optical image with variable magnification is popular because it allows free change of focal length.
As zoom lens systems to be used in interchangeable lens apparatuses, various kinds of zoom lens systems having high optical performance from a wide-angle limit to a telephoto limit have been proposed.
Japanese Laid-Open Patent Publication No. 2007-078799 discloses a variable-magnification optical system comprising a first lens unit composed of a single negative lens, a second lens unit composed of a single positive lens, and a third lens unit composed of a single negative meniscus lens with a concave surface facing an image side.
Japanese Laid-Open Patent Publication No. 2007-078800 discloses a variable-magnification optical system comprising a first lens unit having negative optical power, a second lens unit having positive optical power, and a third lens unit having negative optical power, in which at least one variable-refractive-index optical element is used in the first lens unit.